Cabazitaxel, (αR,βS)-α-hydroxy-β-[[(1,1-dimethylethoxy) carbonyl]amino]benzene-propanoic acid (2aR,4S,4aS,6R,9S,11S,12S,12aR,12bS)-12b-(acetyloxy)-12-(benzoyloxy)-2a,3,4,4a,5,6,9,10,11,12,12a,12b-dodecahydro-11-hydroxy-4,6-dimethoxy-4a,8,13,13-tetramethyl-5-oxo-7,11-methano-1H-cyclodeca[3,4]benz[1,2-b]oxet-9-yl ester, has the following chemical structure:
Cabazitaxel is a semi-synthetic taxoid derivative. It is marketed under the trade name JEVTANA® for the treatment of hormone-refractory prostate cancer.
Cabazitaxel and a process for its preparation are disclosed in U.S. Pat. No. 5,847,170. Cabazitaxel acetone solvate is disclosed in U.S. Pat. No. 7,241,907. Several solid state forms of Cabazitaxel are furthermore disclosed in WO2009/115655 and in WO2012/142117.
Polymorphism, the occurrence of different crystal forms, is a property of some molecules and molecular complexes. A single molecule, like Cabazitaxel, may give rise to a variety of polymorphs having distinct crystal structures and physical properties like melting point, thermal behaviors (e.g. measured by thermogravimetric analysis—“TGA”, or differential scanning calorimetry—“DSC”), powder X-ray diffraction (PXRD) pattern, infrared absorption fingerprint, and solid state NMR spectrum. One or more of these techniques may be used to characterize a particular polymorph and to distinguish different polymorphic forms of a compound.
Different solid state forms (including solvated forms) of an active pharmaceutical ingredient may possess different properties. Such variations in the properties of different solid state forms and solvates may provide a basis for improving formulation, for example, by facilitating better processing or handling characteristics, changing the dissolution profile in a favorable direction, or improving stability (polymorph as well as chemical stability) and shelf-life. These variations in the properties of different solid state forms may also offer improvements to the final dosage form, for instance, if they serve to improve bioavailability. Different solid state forms and solvates of an active pharmaceutical ingredient may also give rise to a variety of polymorphs or crystalline forms, which may in turn provide additional opportunities to assess variations in the properties and characteristics of a solid active pharmaceutical ingredient.
Discovering new polymorphic forms and solvates of a pharmaceutical product can provide materials having, inter alia, desirable processing properties, such as ease of handling, ease of processing, chemical and polymorphic stability upon storage and processing, and ease of purification or are useful as advantageous intermediate crystal forms that facilitate conversion to other solid state forms (including other solvates) of said pharmaceutical product. New polymorphic forms and solvates of a pharmaceutically useful compound can also provide an opportunity to improve the performance characteristics of a pharmaceutical product. It enlarges the repertoire of materials that a formulation scientist has available for formulation optimization, for example by providing a product with different properties, e.g., better processing or handling characteristics, improved dissolution profile, or improved shelf-life. Lastly, new polymorphic forms may be prepared with improved reliability and reproducibility compared to other forms, for example in terms of crystallinity or polymorphic purity.